SFJ/SPJ incompetence

Pathological reflux (backwards flow) of blood from the deep vein system across the saphenofemoral junction (SFJ) or saphenopopliteal junction (SPJ) into the trunk veins through valves that are incompetent (leaky). Valves in healthy veins allow the blood to flow in one direction only, that is to say, towards the heart. When they are leaky, the blood also flows in the opposite direction, towards the feet. Blood collects in the legs and varicose veins develop.